Patent document WO 2012/171105 A1 discloses a test bench for a turbine engine including an energy utilization system. The system recovers the kinetic energy of a mixture of combustion gas and air moving inside the test bench and transforms this kinetic energy into electricity by means of a wind power engine. The turbine engine is situated in a test chamber and the wind power engine is situated in a tube downstream of the test chamber. The tube is commonly called a “collector tube”, in that it collects the combustion gas exiting from the turbine engine. The high speed of the combustion gas in the tube allows a minimum of ambient air to be drawn in around the turbine engine in order to satisfy the required test conditions in terms of minimum air flow in the test chamber. The collector tube in a way plays a role of a pump of the gas mixture with a view to its expulsion, it also prevents localized reversals of the outflow downstream of the turbine engine. The collector tube can in particular be configured to absorb sound waves downstream of the turbine engine. The wind power engine includes blades that have a variable pitch in order to adapt to the different gas mixture flow speeds reached according to the size of the turbine engines under test; it is connected to an alternator/generator in order to generate electricity. This teaching is valuable in that the wind power engine positioned in the collector tube receives a stream of gas mixture that is substantially laminar. Moreover, the tube limits the size of the wind power engine. However, the teaching is limited to tests of turbine engines for which the speed and pressure of the exhaust gas from the turbine engine, modified by the presence of the wind power engine in the tube, always guarantee the minimum drawing-in of test chamber ambient air necessary for the test. Moreover, the position of the wind power engine in the tube receiving a gas mixture of combustion products at high temperature imposes functioning constraints on the wind power engine that increase its cost.
Patent document EP 2 336 507 A1 discloses a test bench for a turbine engine including a turbine intended to recover the kinetic energy of the exhaust gas from the turbine engine. The turbine is placed between a test chamber, upstream, in which the turbine engine is situated, and an exhaust gas expulsion chamber, downstream. The turbine is configured to replace the function of a conventional collector tube, which is generally of a significant length. In particular, the turbine is capable of absorbing sound waves, for example, infrasounds. The turbine rotor on which are mounted the blades, driven in rotation by the kinetic energy of the gas stream, also includes a propeller functioning as a fan so as to balance the air pressures between the test chamber and the expulsion chamber according to the turbine engines under test. This teaching is valuable in that the test bench is substantially compact. However, it is limited to tests of turbine engines for which the exhaust gas temperature does not exceed a threshold critical to the components of the turbine. Moreover, the turbine forms a brake for the outflow of gas downstream of the engine, and localized reversals of the outflow can perturb testing of turbine engines.